Select the list where the message you'd like to view replies for is stored by clicking the Manage button from your lists on the dashboard.

Click the Messaging icon in the list navigation bar in the top right hand corner of your list homescreen.

Find the message you want to view replies for, and click the View Report button for that specific message.

Scroll down the bottom of the message report and you'll see a section titled Responses Received, this is where all your subscriber replies will be stored.